1. Field of the Invention
This present invention relates to an electrical heating device, in particular for a motor vehicle, with a housing in which at least one heat generating element and a plurality of heat dissipating elements, which are configured in parallel layers, are arranged. In the housing a plurality of heat generating elements can be provided. Usually, for each heat generating element two heat dissipating elements are provided, which are mounted on oppositely situated sides of the heat generating element in order to discharge the heat produced by the heat generating element into the medium to be heated. Consequently, the heat dissipating elements are also designated as radiator elements, in particular when thermal dissipation into the air is desired.
The heat generating elements comprise at least one PTC element, on the opposite lateral faces of which electrical strip conductors are situated, through which the PTC element is supplied with current.
2. Description of the Related Art
Generic class-forming electrical heating devices are used in particular for heating air for the air conditioning of the vehicle passenger compartment and are being increasingly used to compensate the disadvantages associated with the reduced thermal dissipation of modern diesel engines, which include the fact that, particularly in the early operating phase of the engine, insufficient heat is available to heat the vehicle passenger compartment or to keep the windscreen free from condensation.
A generic electrical heating device is for example known from EP-A1-1 768 458. The electrical heating device described there has an increased electrical dielectric strength and is particularly suitable for high voltage operation. With this state of the art insulating layers are provided on the outer side of the strip conductors in each case so that the heat dissipating elements are situated, with the intermediate positioning of the insulating layer, on the associated heat generating element and are potential-free. An electrically conducting foreign body located on the electrical heating device and which, for example, touches the heat dissipating elements situated on opposite sides of the heat generating element, does not therefore lead to a short circuit.
As the electrical heating device for the purpose of this invention, apart from an air heater as given in EP-A1-1 768 458, a heater for a liquid medium can also be considered, as is known for example from EP-A1-1 872 986 which originates from the applicant. With this state of the art the heat generating elements are pushed into pockets closed on the underside and they contact these pockets on the inner sides. The pocket side walls, which in each case extend essentially parallel, should be considered as heat dissipating elements for the purpose of this invention. It is of no concern that the heat dissipating elements are each provided as separate components. Rather, the wording according to claim 1 is in each case based on that these are in each case provided on oppositely situated lateral faces of the heat generating element.